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Electrical properties of Si-doped GaAs layers grown on (411)A GaAs substrates by molecular beam epitaxy (MBE) were investigated for applications to GaAs/AlGaAs resonant tunnelling diodes with atomically flat (411)A GaAs/AlGaAs interfaces over an entire device area. These flat interfaces can be realized by MBE under certain growth conditions (growth temperature T s = 580 • C and V/III pressure ratio of less than or equal to 11). When the V/III pressure ratio is high (above 15) for T s = 580 • C, Si-doped GaAs on a (411)A substrate showed an n-type conduction similar to conventional Si-doped GaAs on (100) substrates. (411)A GaAs/AlGaAs interfaces grown under this condition, however, cannot become as flat and as superior as conventional (100) GaAs/AlGaAs interfaces. On the other hand, when the V/III pressure ratio is 7, an Si-doped GaAs layer on (411)A showed p-type conduction. In the case of a V/III pressure ratio of 10.5 and T s = 580 • C, Si-doped GaAs still showed n-type conduction with the compensation ratio γ (≡ (N D + N A )/(N D − N A )) = 2.3. This result suggests that Si can be used as an n-type dopant in GaAs for GaAs/AlGaAs resonant tunnelling diodes grown on (411)A GaAs substrates with atomically flat (411)A GaAs/AlGaAs interfaces.

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Effectively atomically flat interfaces over a macroscopic area (super-flat interfaces) have been achieved in pseudomorphic In x Ga1-x As/Al0.3Ga0.7As (x = 0.0, 0.04, 0.07) quantum wells (QWs) with well widths (L w) of 1.2–11.8 nm grown on (411)A GaAs substrates at 520°C by molecular beam epitaxy (MBE). A single, sharp photoluminescence (PL) peak was observed for each QW over the large area of the wafer (8 mm ×5 mm). The linewidths for narrow QWs (L w = 2.4 nm) were 8.9 meV (x = 0.04) and 9.9 meV (x = 0.07) at 4.2 K, which were about 30% smaller than those of QWs simultaneously grown on conventional (100) GaAs substrates.